Generally, an optical device includes a lens transfer device moving a lens to an optical direction, where the lens transfer device uses an actuator such as an electro-magnetic motor or a piezoelectric actuator as a means for generating a power. A cam or a screw is used as a means for transmitting power generated by the actuator.
Thus, the lens transfer device uses the power generated by the actuator to adjust a focus by moving the lens to an optical direction, whereby auto-focusing function is realized.
Especially, in recent times, mobile terminals and PDAs (personal digital assistants) are largely and frequently mounted with a camera module. The camera module may be equipped with an AF (Auto Focusing) function, and a VCM (Voice Coil Motor) is used for auto focusing function, where the VCM performs the auto focusing function by vertically moving a lens within a predetermined size of space. In order to perform the AF function in the conventional camera module, a lens position is changed to focus on a particular object.
Meanwhile, the electromagnetic wave is in an invisible odorless thing like the air we breathe, and hangs around us to disturb other electromagnetic waves called EMI (Electromagnetic Interference) which in turn can interfere with the performance of various sensitive wireless devices nearby, causing industrial damages, and resulting in fatal influences directly or indirectly on human body.
Particularly, a camera module is mounted on portable terminals, notebooks and other electronic devices generating electromagnetic wave, which may result in erroneous operation of the electronic devices, such that multi-angled researches and technical developments are being waged to reduce the electromagnetic wave.